Research Article |
Corresponding author: Aurelio Ramírez-Bautista ( ramibautistaa@gmail.com ) Academic editor: Franco Andreone
© 2018 Christian Berriozabal-Islas, Aurelio Ramírez-Bautista, Raciel Cruz-Elizalde, Uriel Hernández-Salinas.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Berriozabal-Islas C, Ramírez-Bautista A, Cruz-Elizalde R, Hernández-Salinas U (2018) Modification of landscape as promoter of change in structure and taxonomic diversity of reptile´s communities: an example in tropical landscape in the central region of Mexico. Nature Conservation 28: 33-49. https://doi.org/10.3897/natureconservation.28.26186
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The degree of species loss was assessed by comparing the structure of communities and species diversity of reptiles from three different environments, one natural (tropical evergreen forest [TEF]) and two modified (shaded coffee plantation [SCP] and grazing area [GA]) from the mid portion of the Sierra Madre Oriental, Mexico. The results showed 29 species, 18 in TEF, 13 in SCP and 12 in GA. According to the abundance of each species, the reptile structure for TEF and SCP was similar and they both differed from GA, while the diversity (effective number of species) was the highest for TEF. The percentage of number of species from TEF accounted for 28% more species than SCP and GA, which indicated a species loss of about 70% in disturbed environments. The values of beta diversity were the highest between TEF and GA, followed by SCP and GA and to a lesser degree between TEF and SCP, which indicates that TEF showed a high number of exclusive species. Our results suggest that carrying out long-term studies that include richness and diversity in environments with different levels of disturbance, in addition to including characteristics of natural history, might enhance the development of more efficient conservation strategies for these species.
Alpha diversity, beta diversity, conservation, disturbed environments, taxonomic diversity
The development of agriculture and livestock activities has generated a high loss of original vegetation in diverse ecosystems of the world (
In tropical environments, the decline has been documented for many biological groups, such as arthropods (
Changes in landscape structure influence the conformation of biological communities amongst sites (
In Mexico, tropical forest remnants and transformed environments, such as agricultural and grazing areas make up the current landscape of some biogeographic regions (
We anticipated a high richness and species diversity in a native environment (tropical evergreen forest), compared to two transformed environments (shaded coffee plantation and grazing areas). In addition, we predict a loss of species from native evergreen forest to transformed environments due to turnover of species (i.e. changes in species composition amongst local assemblages,
The study area is located in the central region of Sierra Madre Oriental and within the Natural Protected Area called Corredor Ecológico Sierra Madre Oriental (
Surveys were carried out in tropical evergreen forest (TEF), shaded coffee plantation (SCP) and grazing area (GA) and they were identified according to the vegetation structure as described by
Location of the study area, the transects in green representing the remnants of tropical evergreen forest. Transects in brown colour show shaded coffee plantation and red transects represent grazing areas.
Tropical evergreen forest (TEF): This vegetation type shows ca. 25% of the deciduous plant species, with tree height between 20 and 30 m, with multilayer vegetation, rich in lianas and epiphytes. The herbaceous layer is composed of the species Campelia zononia, Fuirena simplex, Peperomia obtusifolia and Zebrina pendula; while the main arboreal species are Cedrela odorata, Bursera simaruba, Carpodiptera ameliae, Persea schiedeana, Cecropia obtusifolia, Heliocarpus appendiculatus, Dendropanax arboreus, Trema micrantha and Jaegeria macrocephala, amongst others (
Shade coffee plantation (SCP): The SCP represents an important area of the landscape of the region (Salazar Ortiz et al. 2013). This kind of environment contributes to water retention and maintains the temperature and humidity in a manner which is not highly variable and together provides similar microhabitats to the natural forest that is used by different reptile species. Within the area of SCP, there are diverse woody plant species, such as Alchornea latifolia, B. simaruba, C. odorata and Ceiba pentandra (Salazar Ortiz et al. 2013).
Grazing area (GA): In the region, various government programmes have been developed to drive the expansion and utilisation of the grazing areas. Therefore, large areas of land of TEF have been transformed into grazing areas, which has resulted in a homogeneous environment, where the dominant grasses are Paspalum sp and Andropogon sp. (
The fieldwork was carried out from February 2010 to January 2011, in which 12 sampling events were carried out, each with three days of surveys (one day per environment), therefore, there were 36 samplings for each environment. Due to different amounts of areas of TEF, SCP and GA, the region was subdivided into six areas of 32 km2 each (Figure
Sampling was conducted by using direct searches for individuals in different numbers of transects per environment. Individuals were sought in different microhabitat types and habits, such as terrestrial (rocks, holes, logs), aquatic (amongst aquatic vegetation, water bodies) and arboreal (trunks, branches). The sampling period was based on the activity of the species groups. For example, lizards of the genus Anolis and Ctenosaura are diurnal and their activities peak from 0900 h to 1300 h, while Hemidactylus, Lepidophyma and the snakes Thamnophis and Leptodeira have sunset and nocturnal activity approximately from 1900 h to 2200 h (
Recorded specimens were identified in the field using dichotomous keys and released at the same place and the total number of specimens for each species was reported (
To assess the completeness of the inventory for each environment, species accumulation curves were performed (
Rank-abundance curves were performed to assess structure and composition of the species in each community and the dominant and/or rare species for each environment were identified (
Results obtained from the true diversity analysis allowed the comparison of how distant the diversity is amongst communities, as well as the degree of magnitude (percentage) that distinguishes them from each other. To extract the percentage of diversity between communities we used the formula (DBx100)/DA where DA is the value of diversity of community A, and DB is the value of diversity of community B (
To assess the taxonomic diversity for each community of the environments, the taxonomic distinction of
To detect differences in the taxonomic diversity for each environment, the samples were compared (species list per environment) and the regional species pool generated a null model with 1000 re-samplings (
Finally, to determine the values of change in species composition amongst environments, we used the formula β = 1-J (
In this study, 29 species of reptiles were recorded, included in 15 families and 27 genera, with the group of snakes best represented by 19 species (Table
According to the species accumulation curves for each environment, in the TEF environment (Figure
Species accumulation curves for a species of tropical evergreen forest b species of shaded coffee and c for grazing areas.
Species list and abundance of reptiles recorded during the fieldwork and in each analysed environment. TEF = tropical evergreen forest, SCP = shade coffee plantation and GA = grazing areas.
Family | Species | Acronym of species | Abundance | ||
---|---|---|---|---|---|
TEF | SCP | GA | |||
Kinosternidae | Kinosternon herrerai | Z | 8 | ||
Corytophanidae | Basiliscus vittatus | Ñ | 2 | ||
Dactyloidae | Anolis naufragus | C | 8 | 6 | |
Gekkonidae | Hemidactylus frenatus | V | 22 | ||
Iguanidae | Ctenosaura acanthura | Y | 10 | ||
Phrynosomatidae | Sceloporus variabilis | B | 12 | 8 | 29 |
Sphenomorphidae | Scincella gemmingeri | D | 6 | 4 | |
Scincella silvicola | H | 4 | 5 | ||
Teiidae | Holcosus amphigrammus | A | 20 | 13 | |
Xantusiidae | Lepidophyma sylvaticum | L | 3 | ||
Boidae | Boa imperator | G | 5 | ||
Colubridae | Drymarchon melanurus | J | 4 | 5 | |
Drymobius margaritiferus | T | 6 | 9 | ||
Lampropeltis polyzona | I | 4 | |||
Leptophis diplotropis | O | 2 | 2 | ||
Mastigodryas melanolomus | C´ | 3 | |||
Spilotes pullatus | M | 3 | |||
Tantilla rubra | Q | 2 | |||
Dipsadidae | Coniophanes fissidens | E | 5 | 2 | |
Coniophanes imperialis | A´ | 6 | |||
Leptodeira maculata | W | 22 | |||
Ninia diademata | F | 5 | |||
Tropidodipsas sartorii | X | 15 | |||
Elapidae | Micrurus diastema | N | 3 | 2 | |
Natricidae | Nerodia rhombifer | U | 4 | 17 | |
Storeria dekayi | S | 6 | 12 | ||
Thamnophis proximus | B´ | 5 | |||
Viperidae | Atropoides nummifer | P | 2 | ||
Bothrops asper | K | 4 | 1 | ||
Totals | 94 | 64 | 158 |
The abundance-rank curves showed a change in the structure of the communities inhabiting a modified environment. Structure and equity of reptile communities were similar in TEF and SCP, but distinct from GA (Figure
On the other hand, TEF exhibited the highest value of diversity in the effective number of species with D1 = 14.1, which is equivalent to the environment with greatest species richness, followed by SCP with a value of D1 = 10.2 and GA with a similar value to the latter with D1 = 10.1 of effective species. In this section, it is important to point out that the observed equivalences in percentage terms indicated that TEF had 28% more species than SCP and GA.
Curves of rank-abundance of reptiles where community composition is evaluated by type of environment. The species are represented by letters (see Table
Reptile species that are under some risk category according to the NOM-059-2010 or whose distribution is restricted to the study region (see text). H= Scincella silvicola, L= Lepidophyma sylvaticum, Q= Tantilla rubra, P= Atropoides nummifer, Y= Ctenosaura acanthura, T= Drymobius margaritiferus, O= Leptophis diplotropis, N= Micrurus diastema, Z= Kinosternon herrerai, W= Leptodeira maculata, X= Tropidodipsas sartorii and B´= Thamnophis proximus.
The graphs of taxonomic diversity showed that TEF and SCP present similar mean values of taxonomic diversity (58.2 and 58.5, respectively, Delta+; Figure
The richness, diversity and composition of reptile species in the analysed environments were different from each other. The results showed a general pattern of species loss and change in structure communities from preserved forest remnants to areas of SCP and GA. This pattern could be driven by the loss of vegetation cover, as well as loss of water bodies and changes in humidity and temperature amongst places, which together provide appropriate conditions (e.g. ideal microhabitats) to be exploited by different species of reptiles (
Analysis of completeness indicated that there are still species to record in SCP and TEF, while GA showed the highest percentage of completeness. This pattern might be caused by two factors, i) the method used in this study and ii) the complex structure pertaining to each environment. GA showed a low number of microhabitat types which could be occupied by reptile species, including rocky crevices, logs, hollows of trees or water bodies. While the opposite was observed in SCP and TEF, with both sites containing leaf litter, logs, bromeliads and undergrowth at the edge of water bodies. Therefore, heterogeneity in microhabitats tends to make it more difficult to observe all individuals belonging to each species (
Tropical evergreen forest showed the greatest species richness, as well as a high number of exclusive species. These species are represented with low abundance, mainly in the snakes A. nummifer, Boa imperator, Ninia diademata and T. rubra; in contrast, GA had less species richness but showed a high abundance, for example, in H. frenatus, N. rhombifer, S. variabilis and L. maculata (Table
With regards to the equity, this is a measure of species diversity considered in studies on structure and species composition of an environment (see
The results of diversity and composition of communities of reptiles in each environment are supported by a taxonomic diversity analysis (a measure complementary to species diversity), where TEF and SCP were similar in this value of diversity; however, GA showed higher values (Figure
In summary, a change in species number from TEF to SCP and GA showed a pattern of species loss. From TEF to SCP, there was species loss while, from TEF to GA, there was severe loss and replacement by new, supposedly opportunistic species. TEF and SCP, however, maintained a similar diversity and species composition of reptiles, indicating that transformed environments with similar characteristics to the untransformed forest contribute to the persistence of species richness. Therefore, in addition to the analysis of richness, diversity and structure of the reptile communities amongst environments, the size of the patches, edge effect and the surrounding matrix of the fragments of the untransformed forest should also be analysed in order to identify the consequences of these factors on maintenance or loss of species. The assessment of these variables (factors) will allow the recognition of more efficient spatial turnovers. Additionally, maintenance or loss of species amongst environments might change according to the availability of resources (space-food), which in turn are influenced by environmental factors, such as temperature, precipitation and humidity (
The authors would like to thank Jaime M. Calderón Patrón for his logistic help. Thanks to Daniel Lara Tufiño and Luis M. Badillo Saldaña for their help in the field. We also thank Larry David Wilson and Vicente Mata Silva for reading a first draft of the manuscript. We thank three anonymous reviewers for their comments that improved our manuscript. This work was supported by the project FOMIX 2012/191908 and CONABIO JM001. The fieldwork was carried out under the scientific permit provided by Secretaría del Medio Ambiente y Recursos Naturales (SEMARNAT; #SGPA/DGVS/02726/10).